U.S. patent application number 13/473533 was filed with the patent office on 2012-11-22 for high density, hard tip arrays.
This patent application is currently assigned to NanoInk, Inc.. Invention is credited to Nabil A. Amro, Joseph S. Fragala, Jason R. Haaheim, Albert K. HENNING, Raymond Roger Shile.
Application Number | 20120295030 13/473533 |
Document ID | / |
Family ID | 46172935 |
Filed Date | 2012-11-22 |
United States Patent
Application |
20120295030 |
Kind Code |
A1 |
HENNING; Albert K. ; et
al. |
November 22, 2012 |
HIGH DENSITY, HARD TIP ARRAYS
Abstract
Improved high density, hard tip arrays for use in patterning are
provided. An article comprises a handle chip; and a silicon nitride
membrane bonded to at least a portion of the handle chip. The
silicon nitride membrane comprises an array of a plurality of
silicon nitride tips extending directly from a surface of the
silicon nitride membrane. Another article comprises an elastomeric
backing member; and an array of tips disposed on the elastomeric
backing member. The tips of the array comprise a refractory
material. Methods of making such articles are also provided.
Inventors: |
HENNING; Albert K.; (Palo
Alto, CA) ; Shile; Raymond Roger; (Los Gatos, CA)
; Fragala; Joseph S.; (San Jose, CA) ; Amro; Nabil
A.; (Prospect Heights, IL) ; Haaheim; Jason R.;
(Chicago, IL) |
Assignee: |
NanoInk, Inc.
|
Family ID: |
46172935 |
Appl. No.: |
13/473533 |
Filed: |
May 16, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61487212 |
May 17, 2011 |
|
|
|
Current U.S.
Class: |
427/256 ;
118/200; 156/242; 156/250; 156/272.2; 156/60 |
Current CPC
Class: |
G03F 7/0002 20130101;
B82Y 10/00 20130101; B81C 99/009 20130101; B82Y 40/00 20130101;
Y10T 156/1052 20150115; Y10T 156/10 20150115 |
Class at
Publication: |
427/256 ; 156/60;
156/250; 156/272.2; 156/242; 118/200 |
International
Class: |
B05C 1/00 20060101
B05C001/00; B05D 5/00 20060101 B05D005/00; B32B 37/02 20060101
B32B037/02; B32B 37/14 20060101 B32B037/14; B32B 38/10 20060101
B32B038/10 |
Claims
1. An article comprising: a handle chip; and a silicon nitride
membrane bonded to at least a portion of the handle chip, wherein
the silicon nitride membrane comprises an array of a plurality of
silicon nitride tips extending directly from a surface of the
silicon nitride membrane.
2. The article of claim 1, wherein the silicon nitride tips are
nanoscopic tips.
3. The article of claim 1, wherein the silicon nitride membrane is
anodically bonded to the handle chip.
4. The article of claim 1, wherein the handle chip is a pyrex
handle chip.
5. The article of claim 1, wherein the handle chip comprises at
least one hole region, and a portion of the silicon nitride
membrane extends across the hole region.
6. The article of claim 1, wherein the handle chip comprises at
least one hole region, and an elastomeric backing member for the
tip array disposed in the hole region.
7. The article of claim 1, wherein the handle chip comprises at
least one hole region, and a polysiloxane backing layer for the tip
array disposed in the hole region.
8. The article of claim 1, wherein the tip array is totally free of
cantilevers.
9. The article of claim 1, wherein the array of tips is
characterized by a tip density of at least 250,000 per square
cm.
10. (canceled)
11. The article of claim 1, wherein the tips of the tip array are
characterized by a tip radius of about 250 nm or less.
12.-15. (canceled)
16. The article of claim 1, wherein the tip array is characterized
by a tip spacing of about 1 micron to about 100 microns.
17.-18. (canceled)
19. The article of claim 1, wherein the silicon nitride membrane
has a thickness of about 100 nm to about one micron.
20. (canceled)
21. A method comprising: preparing a silicon nitride membrane
comprising an array of a plurality of silicon nitride tips
extending directly from a surface of the silicon nitride membrane;
preparing a handle wafer; and bonding the silicon nitride membrane
to at least a portion of the handle wafer to form an bonded tip
array.
22. The method of claim 21, further comprising the step of dicing
the bonded tip array.
23. The method of claim 21, wherein the bonding is an anodical
bonding.
24. The method of claim 21, wherein the handle wafer is a pyrex
handle wafer.
25. The method of claim 21, wherein the handle wafer comprises at
least one hole region, and a portion of the silicon nitride
membrane extends across the hole region.
26. The method of claim 21, wherein the tip array is totally free
of cantilevers.
27. The method of claim 21, wherein the tip array is totally free
of silicon tips.
28. The method of claim 21, wherein the silicon nitride is low
stress silicon nitride.
29. (canceled)
30. The method of claim 21, wherein: the handle wafer comprises at
least one hole region, a portion of the silicon nitride membrane
extends across the hole region, and the method further comprises
the step of disposing an elastomeric backing member in the hole
region.
31. The method of claim 21, wherein: the handle wafer comprises at
least one hole region, a portion of the silicon nitride membrane
extends across the hole region, the silicon nitride membrane
comprises a plurality of perforations surrounding at least part of
the portion of the silicon nitride membrane that extends across the
hole region, and the method further comprises: disposing an
elastomeric backing member in the hole region, and pressing the
elastomeric backing member against a back surface of the silicon
nitride membrane such that the part of the silicon nitride membrane
surrounded by the plurality of perforations separates from a
remainder of the silicon nitride membrane and attaches to the
elastomeric backing member.
32. An article comprising: an elastomeric backing member; and an
array of tips disposed on the elastomeric backing member, wherein
the tips of the array comprise a refractory material.
33. The article of claim 32, wherein the refractory material is a
refractory metal.
34. The article of claim 32, wherein the refractory material is Nb,
Mo, Ta, W, Ru, Ti, V. Cr, Zr, Ru, Rh, Hf, Os, or Ir.
35. The article of claim 32, wherein the refractory material is Nb,
Mo, Ta, W, or Ru.
36. The article of claim 32, wherein the refractory material is
Cr.
37. The article of claim 32, wherein the refractory material is W,
diamond, a carbide, or a boride.
38. The article of claim 32, wherein the elastomeric backing member
comprises polysiloxane.
39. The article of claim 32, wherein the tips are nanoscopic
tips.
40. The article of claim 32, wherein the array is formed by a
plurality of noncontinuous islands on the elastomeric backing
member, each island comprising a single tip.
41. (canceled)
42. A method comprising: providing at least one mold for a tip
array comprising a plurality of mold regions for tips; filling or
coating the mold regions for tips with a refractory material, to
form an array of tips comprising a refractory material; and
attaching an elastomeric backing member to the refractory material
of the tips.
43. The method of claim 42, wherein the step of attaching the
elastomeric backing member comprises: disposing a liquid elastomer
precursor material in contact with the refractory material of the
tips; and curing the liquid elastomer precursor material while the
elastomer precursor material remains in contact with a surface of
the tips.
44. The method of claim 42, wherein the elastomeric backing member
comprises siloxane.
45. The method of claim 42, wherein the refractory material is a
refractory metal.
46. The method of claim 42, wherein the refractory material is Nb,
Mo, Ta, W, Ru, Ti, V, Cr, Zr, Ru, Rh, Hf, Os, or Ir.
47.-48. (canceled)
49. The method of claim 42, wherein the refractory material is W,
diamond, a carbide, or a boride.
50. The method of claim 42, wherein the tips of the refractory
material are patterned so as to form non-continuous islands, with
each island covering each elastomer tip.
51. The method of claim 42, wherein the refractory material is
coated to a thickness of about 250 nm to about 750 nm.
52. The method of claim 42, wherein the elastomer backing material
comprises elastomer tips integral with elastomer backing.
53. A method comprising: providing the article of claim 1,
disposing at least one patterning composition on the tip array,
transferring the ink from the tip array to a substrate surface.
54. A method comprising: providing the article of claim 32,
disposing at least one patterning composition on the tip array,
transferring the ink from the tip array to a substrate surface.
55. An article comprising: at least one silicon nitride tip array,
wherein the tip array is substantially free of cantilevers, at
least one handle chip, wherein the tip array is bonded to the at
least one handle chip.
56. An article comprising: an elastomeric backing member; and a
silicon nitride membrane bonded to at least a portion of the
elastomeric backing member, wherein the silicon nitride membrane
comprises an array of a plurality of silicon nitride tips extending
directly from a surface of the silicon nitride membrane.
57. The article of claim 56, wherein the silicon nitride tips are
nanoscopic tips.
58. The article of claim 56, wherein the array of tips is
characterized by a tip density of at least 100,000 per square
cm.
59.-60. (canceled)
61. The article of claim 56, wherein the tips of the tip array are
characterized by a tip radius of about 250 nm or less.
62.-65. (canceled)
66. The article of claim 56, wherein the tip array is characterized
by a tip spacing of about 1 micron to about 100 microns.
67.-68. (canceled)
69. The article of claim 56, wherein the silicon nitride membrane
has a thickness of about 100 nm to about one micron.
70. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from U.S. Provisional
Patent Application No. 61/487,212, filed May 17, 2011, which is
hereby incorporated by reference in its entirety.
BACKGROUND
[0002] In the context of stamp and tip-based microscale and
nanoscale patterning, various modalities of tips (hard and soft,
sharp and rounded, and permeable and impermeable) have been
demonstrated over the last fifteen years approximately. The
modalities have been described by a variety of names including, for
example, microcontact printing, soft lithography,
dip-pen-nanolithography, scanning probe contact printing,
microstamp patterning, and the like. See, for example, U.S. Pat.
Nos. 6,635,311; 6,827,979; and 7,344,756.
[0003] In some cases, these tips have been intended to achieve the
goal of large-area fabrication of microstructures and
nanostructures, without the requirement of a conventional
photolithographic mask. Recently, hard silicon tips with a soft
backing have been proposed as a preferred means to accomplish this
goal. See, for example, Shim, et al., "Hard tip, soft-spring
lithography", Nature, (469) pp 516-520, 2010 and also WO
2010/141,836 (Mirkin et. al., Northwestern Univ.). However, in the
context of manufacturable and reliable tip-based patterning,
silicon suffers as a tip material because, for example, its
crystalline structure leads to fracture at relative low macroscale
forces for the lithographic system--forces which can occur even
with a soft backing in some embodiments, at least. Silicon tips
also experience undesired wear over extended use and become duller.
In addition, use of some tip materials of interest may cause
fabrication problems. Also, some tips may fall off of their
supporting structure.
[0004] A need exists for better tip systems and methods for making
the same.
SUMMARY
[0005] Embodiments described herein include articles, methods of
making, and methods of using. Kits can also be provided.
[0006] For example, one embodiment provides an article comprising:
at least one silicon nitride tip array, wherein the tip array is
substantially free of cantilevers, at least one handle chip,
wherein the tip array is bonded to the at least one handle
chip.
[0007] Another embodiment provides a method comprising: preparing a
silicon nitride tip array which is substantially free of
cantilevers, preparing a handle wafer, and bonding the tip array to
the handle wafer to form a bonded tip array.
[0008] Another embodiment provides an article comprising: at least
one elastomeric tip array, wherein the tips of the tip array
comprise a surface layer of refractory material.
[0009] Another embodiment provides a method comprising: providing
at least one mold for a tip array comprising a plurality of mold
regions for tips, coating the mold regions for tips with a
refractory material, filling the mold regions for tips with an
elastomeric material so that elastomeric material is in contact
with the refractory material and forms at least one elastomeric tip
array, wherein the tips of the tip array comprise a surface layer
of refractory material upon removal from the mold.
[0010] Elastomeric material, such as a polysiloxane like PDMS
(polydimethylsiloxane) also can be a precursor to an elastomeric
material including a precursor to a polysiloxane or PDMS.
[0011] Another embodiment provides a method comprising: providing
the silicon nitride tip arrays as described herein, disposing at
least one patterning composition on the tip array, transferring the
composition from the tip array to a substrate surface. For example,
biological materials like proteins and nucleic acids can be
patterned.
[0012] Another embodiment provides a method comprising: providing
an elastomeric tip array comprising refractory material, as
described herein, disposing at least one patterning composition on
the tip array, transferring the composition from the tip array to a
substrate surface. Again, for example, biological materials like
proteins and nucleic acids can be patterned.
[0013] In addition, embodiments described herein include modalities
of microscale and nanoscale patterning, using either: (A) silicon
nitride membranes, with high-density arrays of intentionally either
sharp or rounded tips silicon nitride, with a soft/compliant, for
example, PDMS backing for contact force management; or, (B)
high-density arrays of refractory metal tips (Cr, for example),
again backed by, for example, PDMS, Covering an area of
approximately 1 cm.sup.2, arrays built with these other modalities
can be large enough to be effective for manufacturing. They can be
hard enough to hold their shape reliably for many cycles. The close
spacing of the tips can offer high speed patterning compared to a
lower density array. In addition, the shape of the tips in these
arrays can be controlled to a high degree, offering
high-performance. The hard tips can resist deformation leading to
higher fidelity of small printed spots. Compared to soft polymer
tips, the spot size can be independent of tip force leading to much
more uniform patterns across the printed area. Compared to tips on
cantilevers, the tip density can be higher resulting in faster
printing of dense patterns. When combined with a precision position
system, a lithographic system based on these arrays can achieve at
least some of and in some cases many of the requirements. For
example, the tips can be relatively stable on their support
structure and do not fall off.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIGS. 1A-1D illustrate an embodiment for a SiN membrane
array. FIG. 1A is a top plan view of the array; FIG. 1B is a top
plan magnified view of the portion of the array labeled "Detail A"
in FIG. 1A; FIG. 1C is a cross-sectional view of the array taken
along the line X-X of FIG. 1A; and FIG. 1D is a cross-sectional
magnified view of the portion of the array labeled "Detail B" in
FIG. 1C.
[0015] FIG. 2 illustrates an embodiment for a SiN membrane array
(higher magnification of a square array).
[0016] FIG. 3 illustrates an embodiment for a SiN membrane array
(lower magnification of a square array).
[0017] FIG. 4 illustrates an embodiment for a SiN membrane array
(perspective view of entire tip array including handle and hole
region).
[0018] FIGS. 5A-5D illustrate an embodiment for the refractory tip
array, FIG. 5A being a top plan view of the array, FIG. 5B being a
top plan magnified view of the portion of the array laveled "Detail
C" in FIG. 5A, FIG. 5C being a cross-sectional view of the array
taken along the line Y-Y of FIG. 5A, and FIG. 5D being a
cross-sectional magnified view of the portion of the array labeled
"Detail D" in FIG. 5C.
[0019] FIG. 6 illustrates an embodiment for a refractory tip
array.
[0020] FIG. 7 illustrates an embodiment for a refractor tip
array.
[0021] FIG. 8 illustrates an embodiment for a refractory array.
[0022] FIG. 9A shows for one embodiment an optical image of a SiN
HD tip membrane having perforations, and FIG. 9B also shows an
embodiment for a top plan view of a SiN HD tip membrane having
perforations.
[0023] FIG. 10 shows for one embodiment a process for mounting a
SiN HD tip membrane on an elastomeric backing member.
[0024] FIG. 11 shows for one embodiment a top plan magnified view
of a portion of a SiN HD tip membrane having perforations.
[0025] FIGS. 12A-12F show various possible configurations of the
perforations in a SiN HD tip membrane.
[0026] FIG. 13 shows for one embodiment a side view of an SiN HD
tip membrane disposed on an elastomeric backing member (in this
case, PDMS).
[0027] FIG. 14 shows for one embodiment SEM images of various
portions of a patterned substrate, demonstrating the consistency of
patterning at the four corners of the substrate.
[0028] FIG. 15 shows for one embodiment SEM images of various
portions of a patterned substrate, demonstrating the consistency of
patterning at the four corners of the substrate.
[0029] FIG. 16A shows for one embodiment a process for filling a
refractory material (in this case, Cr) in a mold (in this case,
Si), showing both partial filling of the mold recesses (on the
bottom left), and complete filling of the mold recesses (on the
bottom right), and FIG. 16B shows top and top perspective views of
non-continuous islands of refractory material tips on a mold.
[0030] FIGS. 17A-17C show for one embodiment a process for forming
an array of refractory material tips (in this case, Cr tips) on an
elastomeric backing member (in this case, a PDMS backing member),
FIG. 17A showing the step of pouring a liquid PDMS precursor into a
container to surround a Cr/Si mold and a spacer, FIG. 17B showing a
curing step, FIG. 17C showing a step of disposing the cured PDMS
backing member and Cr/Si mold into an etching solution to remove
the Si, FIG. 17D showing the PDMS backing member and Cr tips after
etching, and FIG. 17E showing the Cr tips disposed on the PDMS
backing member after dicing.
DETAILED DESCRIPTION
Introduction
[0031] All references cited herein are incorporated by reference in
their entirety.
[0032] Priority U.S. Provisional Patent Application No. 61/487,212,
filed May 17, 2011, is hereby incorporated by reference in its
entirety including the claims and drawings and examples.
[0033] The following references can be used in the practice of the
various embodiments described herein including patterning methods
and compositions: [0034] 1. Wilbur, et al., "Microcontact printing
of self-assembled monolayers: applications in microfabrication."
Nanotechnology 7, pp. 452-457 (1996). [0035] 2. Biebuyck, et al.,
"Lithography beyond light: Microcontact printing with monolayer
resists." IBM J. Res. Dev. 41(1/2), pp. 159170 (1997). [0036] 3.
Xia et al., "Soft lithography." Ann. Rev. Mat. Sci. 28, pp. 153-184
(1998). [0037] 4. Wang, et al., "Scanning Probe Contact Printing."
Langmuir 19(21), pp. 8951-8955 (2003). [0038] 5. Zou, et al.,
"Conductivity-based contact sensing for probe arrays in dip-pen
nanolithography." Appl. Phys. Lett. 83(3), pp. 581583 (2003).
[0039] 6. Liu, et al., "Scanning probe microscopy probes and
methods." U.S. Pat. No. 7,081,624 (25 Jul. 2006). [0040] 7. Mirkin,
et al., "Method for scanning probe contact printing." U.S. Pat. No.
7,344,756 (18 Mar. 2008). [0041] 8. Li, et al., "Pneumatically
actuated elastomeric device for nanoscale surface patterning."
Appl. Phys. Lett. 91(2), pp. 023109-1ff (2007). [0042] 9. Xia, et
al., "Reduction in the Size of Features of Patterned SAMs Generated
by Microcontact Printing with Mechanical Compression of the Stamp,"
Adv. Mater. 7, pp. 471-473 (1995). [0043] 10. A. Kumar and G. M.
Whitesides, "Formation of microstamped patterns on surfaces and
derivative articles." U.S. Pat. No. 5,512,131 (30 Apr. 1996).
[0044] 11. G. M. Whitesides, et al., "Microcontact printing on
surfaces and derivative articles." U.S. Pat. No. 6,180,239 (30 Jan.
2001). [0045] 12. Hong, et al., "A Nanoplotter with Both Parallel
and Serial Writing Capabilities." Science 288(5472), pp. 1808-1811
(9 Jun. 2000). [0046] 13. Mirkin, et al., "Multiscale Soft Pen
Lithography." U.S. Patent Provisional Application, 27 Jun. 2008.
[0047] 14. Ginger, et al., "The evolution of dip-pen
nanolithography." Angew. Chem. Int. Ed. 43, pp. 30-45 (2004).
[0048] 15. Zhang, et al., "Dip pen nanolithography stamp tip," Nano
Lett 4(9), pp. 1649-1655 (2004). [0049] 16. Shim, et al., "Hard
tip, soft-spring lithography", Nature, (469) pp 516-520, 2010.
[0050] 17. Hong, et al., "A Micromachined elastomeric tip array for
contact printing with variable dot size and density", Journal of
Micromechanics and Microengineering, 1815003 (2008).
[0051] Transfer of inks from tips, which can be carried out with
use of the tip arrays described herein, are described in technical
literature including, for example, U.S. Pat. Nos. 6,635,311;
6,827,979; 7,102,655; 7,223,438; 7,273,636; 7,291,284; 7,326,380;
7,344,756; and 7,361,310. A wide variety of inks can be patterned
including inorganic, organic, biological, low molecular weight,
polymeric, particulate, and nanostructured materials.
[0052] Embodiments described herein can provide hard tip arrays. In
one embodiment, hard silicon nitride tip arrays are prepared. In
another embodiment, tip arrays comprising surfaces of refractory
materials such as chromium can be prepared. In each case, the
disadvantage of using silicon tips can be avoided. In particular,
silicon tips can be substantially or totally excluded from the tip
arrays.
[0053] In one embodiment, the tip array is totally free of
cantilevers. In one embodiment, the tip array is totally free of
silicon tips.
SiN Membrane Arrays
[0054] One embodiment provides an article comprising: at least one
silicon nitride tip array, wherein the tip array is substantially
free of cantilevers, at least one handle chip, wherein the tip
array is bonded to the at least one handle chip. In one embodiment,
the silicon nitride tip array comprises low stress silicon
nitride.
[0055] In one embodiment, an article comprises a handle chip; and a
silicon nitride membrane bonded to at least a portion of the handle
chip. The silicon nitride membrane comprises an array of a
plurality of silicon nitride tips extending directly from a surface
of the silicon nitride membrane. The silicon nitride membrane can
be a monolithic integrated structures wherein the tips are a part
of the support structure. This can provide added stability so the
tips do not fall off of the support structure.
[0056] Handle chips are known in the art. See, for example, US
Patent Publication 2011/0268883.
[0057] The tips can be adapted to provide for disposing an ink
composition on the tip and then transferring the ink from the tip
to a substrate. In one embodiment, the tip array is a nanoscopic
tip array. If desired, the tips can be surface coated.
[0058] Bonding methods are known in the art. In one embodiment, the
tip array is anodically bonded to the at least one handle chip.
[0059] Materials for making a handle chip are known in the art. In
one embodiment, the handle chip is a pyrex handle chip. The handle
chip can also be called a support.
[0060] In one embodiment, the handle chip comprises at least one
hole region. In one embodiment, furthermore, the handle chip
comprises at least one hole region, and an elastomeric backing
layer for the tip array disposed in the hole region. In one
embodiment, for example, the handle chip comprises at least one
hole region, and a polysiloxane backing layer for the tip array
disposed in the hole region.
[0061] In one embodiment, the array of tips is characterized by a
tip density of at least 100,000 per square cm. In one embodiment,
the array of tips is characterized by a tip density of at least
250,000 per square cm. In one embodiment, the array of tips is
characterized by a tip density of at least 1,000,000 per square
cm.
[0062] In one embodiment, the tips of the tip array are
characterized by a tip radius of about 250 nm or less. In one
embodiment, the tips of the tip array are characterized by a tip
radius of about 100 nm or less. In one embodiment, the tips of the
tip array are characterized by a tip radius of about 50 nm or less.
In one embodiment, the tips of the tip array are characterized by a
tip radius of about 20 nm or less.
[0063] In one embodiment, the tip array has an area of at least one
square cm. In another embodiment, the tip array has an area of less
than one square cm. In one embodiment, the tip array is
characterized by a tip spacing of about 1 micron to about 100
microns. In one embodiment, the tip array is characterized by a tip
spacing of about 5 microns to about 50 microns. In one embodiment,
the tip array is characterized by a tip spacing of about 10 microns
to about 30 microns.
[0064] In one embodiment, the tip array has a thickness of about
100 nm to about one micron. In one embodiment, the tip array has a
thickness of about 400 nm to about 800 nm. In one embodiment, the
thickness is about 600 nm.
[0065] FIGS. 1A-1D illustrate an embodiment. In FIG. 1A, a top view
is shown for the silicon nitride membrane and tip array with a
square array of tips. Also shown is the pyrex support including the
hole region. In FIG. 1B, an expanded form of the tip array region
is illustrated, showing pyramidal tips. In FIG. 1C, a side, cross
sectional view is shown. In FIG. 1D, an expanded view of the tip
array region is illustrated.
[0066] In one embodiment, the tip array is totally free of
cantilevers. In one embodiment, the tip array is totally free of
silicon tips.
Method of Making SiN Arrays
[0067] One embodiment provides a method comprising: preparing a
silicon nitride tip array which is substantially free of
cantilevers, preparing a handle wafer, and bonding the tip array to
the handle wafer to form an bonded tip array.
[0068] In one embodiment, the embodiment further comprises the step
of dicing the bonded tip array.
[0069] In one embodiment, the bonding is an anodical bonding.
[0070] In one embodiment, the handle wafer is a pyrex handle
wafer.
[0071] In one embodiment, the handle wafer comprises at least one
hole region.
[0072] In one embodiment, the tip array is totally free of
cantilevers.
[0073] In one embodiment, the tip array is totally free of silicon
tips.
[0074] In one embodiment, the silicon nitride is low stress silicon
nitride.
[0075] In one embodiment, the tip array is a square tip array.
[0076] In one embodiment, the embodiment further comprises the step
of disposing an elastomeric backing in the hole region.
[0077] In one embodiment, a method comprises preparing a silicon
nitride membrane comprising an array of a plurality of silicon
nitride tips extending directly from a surface of the silicon
nitride membrane; preparing a handle wafer; and bonding the silicon
nitride membrane to at least a portion of the handle wafer to form
an bonded tip array.
[0078] In one embodiment, the handle wafer comprises at least one
hole region, a portion of the silicon nitride membrane extends
across the hole region, and the method further comprises the step
of disposing an elastomeric backing member in the hole region.
[0079] In one embodiment, the handle wafer comprises at least one
hole region, a portion of the silicon nitride membrane extends
across the hole region, the silicon nitride membrane comprises a
plurality of perforations surrounding at least part of the portion
of the silicon nitride membrane that extends across the hole
region, and the method further comprises disposing an elastomeric
backing member in the hole region, and pressing the elastomeric
backing member against a back surface of the silicon nitride
membrane such that the part of the silicon nitride membrane
surrounded by the plurality of perforations separates from a
remainder of the silicon nitride membrane and attaches to the
elastomeric backing member. An example of this embodiment is
illustrated in FIGS. 9A, 9B, and 10.
[0080] FIG. 9A is an optical image of a SiN HD tip membrane having
perforations, and FIG. 9B is a top plan view of a SiN HD tip
membrane having perforations.
[0081] The top image of FIG. 10 illustrates a silicon nitride
membrane comprising an array of silicon nitride tips extending from
a surface (the top surface in FIG. 10). The SiN membrane is
attached to a handle wafer (such as a Si handle wafer) that has a
hole region, such that a portion of the SiN membrane extends across
the hole region. The SiN membrane includes perforations that
surround the portion of the SiN membrane that extends across the
hole region of the handle wafer. A flat elastomeric backing member
(in this case, a PDMS block) disposed in the hole region of the
handle wafer and aligned with the perforations, as shown in the
second image from the top in FIG. 10. Next, the backing member is
pressed against the back surface of the SiN membrane (the bottom
surface in FIG. 10) such that the part of the SiN membrane
surrounded by the perforations separates from a remainder of the
SiN membrane, as shown in the third image from the top in FIG. 10.
The SiN membrane thus attaches to the backing member, as shown in
the bottom image of FIG. 10.
[0082] FIG. 11 is a top plan magnified view of a portion of a SiN
HD tip membrane having perforations. A variety of possible
perforation designs are possible. For example, length P of the
perforations and distance between perforations T, may be set as
indicated in Table 1 below, and shown in FIGS. 12A-12F.
TABLE-US-00001 TABLE 1 FIG. Tab, T(.mu.) Perforation, P(.mu.) 12A
10 50 12B 30 30 12C 50 10 12D 20 100 12E 60 60 12F 100 20
[0083] FIG. 13 shows an example of a SiN membrane HD tip array over
a PDMS backing member that can be created using the above
methods.
Applications
[0084] The tip arrays can be used for patterning and transfer of
ink compositions from the tip to a surface. For example, FIGS. 14
and 15 show SEM images of various portions of patterned substrates
formed using a SiN membrane HD tip array on a PDMS backing member,
demonstrating the consistency of patterning at the four corners of
the substrates.
Refractory Tip Arrays
[0085] One embodiment, in addition, provides an article comprising:
at least one elastomeric tip array, wherein the tips of the tip
array comprise a surface layer of refractory material. Refractory
materials and metals are known in the art. In one embodiment, the
refractory material has a melting point higher than 2,000.degree.
C., or alternatively, higher than 4,000.degree. C.
[0086] In one embodiment, an article comprises an elastomeric
backing member; and an array of tips disposed on the elastomeric
backing member. The tips of the array comprise a refractory
material.
[0087] In one embodiment, the refractory material is a refractory
metal.
[0088] In one embodiment, the refractory material is Nb, Mo, Ta, W,
Ru, Ti, V, Cr, Zr, Ru, Rh, Hf, Os, or Ir.
[0089] In one embodiment, the refractory material is Nb, Mo, Ta, W,
or Ru.
[0090] In one embodiment, the refractory material is Cr.
[0091] In one embodiment, the refractory material is W, diamond, a
carbide, or a boride.
[0092] In one embodiment, the elastomeric tip array is a
polysiloxane tip array.
[0093] In one embodiment, the tips of the elastomeric tip array are
nanoscopic tips.
[0094] In one embodiment, the tips of the refractory material form
non-continuous islands, with each island covering each elastomer
tip.
[0095] In one embodiment, the tip array is a square array.
[0096] FIGS. 5A-5D illustrate additional embodiments for use of
refractory materials and islands of refractory materials. The
elastomer tips can be a monolithic integrated structures wherein
the tips are a part of the support structure. In the array, the
elastomer backing material can comprise elastomer tips integral
with elastomer backing. This can provide added stability so the
tips do not fall off of the support structure.
Method of Making Refractory Tip Arrays
[0097] Another embodiment provides a method comprising: providing
at least one mold for a tip array comprising a plurality of mold
regions for tips, coating the mold regions for tips with a
refractory material, filling the mold regions for tips with an
elastomeric material so that elastomeric material is in contact
with the refractory material and forms at least one elastomeric tip
array, wherein the tips of the tip array comprise a surface layer
of refractory material upon removal from the mold.
[0098] In one embodiment, the elastomer material is curable to form
an elastomeric material.
[0099] In one embodiment, the elastomer material is a siloxane.
[0100] In one embodiment, the refractory material is a refractory
metal.
[0101] In one embodiment, the refractory material is Nb, Mo, Ta, W,
Ru, Ti, V, Cr, Zr, Ru, Rh, Hf, Os, or Ir.
[0102] In one embodiment, the refractory material is Nb, Mo, Ta, W,
or Ru.
[0103] In one embodiment, the refractory material is Cr.
[0104] In one embodiment, the refractory material is W, diamond, a
carbide, or a boride.
[0105] In one embodiment, the tips of the refractory material are
patterned so as to form non-continuous islands, with each island
covering each elastomer tip. In one embodiment, the refractory
material is coated to a thickness of about 250 nm to about 750 nm,
or about 300 nm to about 500 nm, or about 400 nm.
[0106] FIG. 16A shows a process for filling a refractory material
(in this case, Cr) in a mold (in this case, Si), showing both
partial filling of the mold recesses (on the bottom left), and
complete filling of the mold recesses (on the bottom right). FIG.
16B shows top and top perspective views of non-continuous islands
of refractory material tips on a mold (in this case, Cr tips formed
in a Si mold).
[0107] FIGS. 17A-17C show a process for forming an array of
refractory material tips (in this case, Cr tips) on an elastomeric
backing member (in this case, a PDMS backing member). FIG. 17A
shows the step of pouring a liquid PDMS precursor into a container
to surround a Cr/Si mold and a spacer. FIG. 17B showing a curing
step. FIG. 17C shows a step of disposing the cured PDMS backing
member and Cr/Si mold into an etching solution (TMAH) to remove the
Si. FIG. 17D shows the PDMS backing member and Cr tips after
etching. FIG. 17E shows the Cr tips disposed on the PDMS backing
member after dicing.
EXAMPLES
Example 1
Method of Making SiN Membranes
[0108] 1. Grow 1500 .ANG. silicon oxide
[0109] 2. Pattern tip mold squares
[0110] 3. Etch oxide
[0111] 4. Etch Si tip molds in KOH
[0112] 5. Grow 5000 .ANG. sharpening oxide (optional)
[0113] 6. Pattern and etch sharpening oxide (optional)
[0114] 7. Deposit 600 nm low stress silicon nitride
[0115] 8. Oxidize silicon nitride
[0116] 9. Remove nitride from side opposite tip molds
[0117] 10. Prep Pyrex wafer with through holes (using DRIE in AOE
or HF etch or impact grinding or patterned powder blasting)
[0118] 11. Clean Si and Pyrex wafers
[0119] 12. Align and anodically bond nitride wafer to Pyrex
wafer
[0120] 13. Dice
[0121] 14. Etch silicon mold wafer in TMAH or KOH
[0122] 15. Rinse in DI water and dry
[0123] 16. Add PDMS to backside of diaphragm (in the hole drilled
into Pyrex) to add strength and stiffness to diaphragm
(optional)
[0124] FIGS. 2-4 show photographs of an embodiment for the SiN
array.
Example 2
Method of Making Refractory Tips
[0125] Procedure for HD tips, Hard tips/soft backing
[0126] 1. Grow 1500 .ANG. silicon oxide
[0127] 2. Pattern tip mold squares
[0128] 3. Etch oxide
[0129] 4. Etch Si tip molds in KOH
[0130] 5. Grow 5000 .ANG. sharpening oxide (optional)
[0131] 6. Pattern and etch sharpening oxide (optional)
[0132] 7. Deposit antistiction film (optional)
[0133] 8. Sputter 4000 .ANG.tip material (Cr or other hard material
eg Ir, Os, W, Diamond, Carbides, Borides, etc.)
[0134] 9. Pattern to etch Cr into individual squares in and around
each tip mold, but not interconnected
[0135] 10. Strip resist
[0136] 11. Dice into pieces
[0137] 12. Clean
[0138] 13. Put into mold and cast PDMS or other polymer
[0139] There are two options for PDMS steps (14a and 14b):
[0140] 14a. [0141] Cast 1: 10 ratio Siliguard Dupont PDMS on
FDTS-treated silicon area (chrome is NOT FDTS-treated). [0142] Cure
for about 2 hrs at 70 deg C., or overnight [0143] Peel PDMS from
mold with Cr tips attached to PDMS block. [0144] Use optical/AFM
inspection to verify integrity of Cr tips
[0145] 14b. [0146] Cast 1: 10 ratio Siliguard Dupont PDMS on
NON-FDTS-treated silicon; this should happen immediately after
plasma cleaning between 1-5 minutes [0147] Cure for about 2 hrs at
70 deg C., or overnight [0148] Protect PDMS with photoresist that
does not dissolve, etch, or melt in the silicon etch-resist
solution [0149] Remove silicon using etch-resist (such as TMAH),
overnight, warm or boiling [0150] Verify etch end-point detection
(want to stop just as getting to PDMS and chrome, but not too much
after) using one of or a combination of LFM, XPS, or optical
inspection.
[0151] FIGS. 6-8 show photographs of an embodiment for the
refractory material arrays.
* * * * *